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UV ovens for Stone Industry: how they are used and how they works

Introduction

Photo Electronics operates in the drying ovens sector, and today we are one of the leading companies in UV technology for stone. Photo Electronics produces a wide range of UV ovens for drying and hardening single-component mastics, resins and fillers, using the very latest technology and solutions. 

Single-component products are often used to fill and finish materials; these products harden under the Ultraviolet rays emitted by special lamps. Photo Electronics uses high emission Metal Halide lamps in its UV ovens, to exploit the advantages of single-component products in the best possible way. 

Purpose of the system

The purpose is to harden single-component UV mastics and fillers used on natural marble or agglomerates before polishing.

The filling process

This process eliminates the surface faults in soft and porous stone materials using special single-component mastics or fillers. The single-component product doesn’t need an hardener. The raw material is loaded on the line to be dried and heated, then the single-component mastic is applied. The product is applied by hand using spatulas or with automatic batching and application systems. Then the material moves forwards on the roller conveyor and goes into the UV oven, where the hardening process takes just 30/40 seconds. After going through the oven the material has fully hardened and can be polished immediately, without having to wait

Fillers harden in line, rapidly and without wasting time. 

Photo Electronics ovens are highly efficient and productive!

The UV functional principle

The single-component mastic isn’t hardened by exposure to heat, but with invisible electromagnetic waves called UV rays, generated by special UV lamps. The mastic applied on the surfaces of the raw material only hardens when the UV rays irradiate the surface and penetrate into the material. Before going into the oven, the mastic remains in a liquid, semisolid or solid state just as it was in the tin, and can be worked and moulded at ease by the operator. The temperature of the environment and the material has no effect on the hardening. Then the material goes into the UV oven for “UVCuring”. During this process, the product starts to harden rapidly and the process takes just 30/40 seconds. When the material comes out of the UV oven, the fully hardened surfaces can be polished immediately. 

The single-component UV product doesn’t require an hardener. The product hardens
in just 30 seconds. 

UV ovens are extremely compact and can be installed in existing lines.

Composition of the system

  • The Oven consists of a steel tunnel containing: the UV lamps complete with reflectors, the fumes extraction system, various screens and sheet steel covers reaching the ground. 
  • An electrical board (specific) lets the user manage the oven. 
  • The Oven is independent from the conveyor system. Infact, it is designed to adapt to any kind of roller conveyor or rack and can be moved or fixed. 
  • An integrated blower permits to extract and expel fumes generated by resins and channel them to the outside or to a solvents suppression system. 
  • An additional cooling system rationally distributes clean air for cooling the lamp units, air which can be taken from outside the building. 
  • They are designed in compliance with the Machinery Directive 98/37/EC and ATEX 94/9/EC. 
  • Each lamp unit is easily removable without the use of tools, and this allows to easily inspect the interior of the tunnel. 
  • A safety devices switch off each Lamp Unit if it is raised while operating. 
  • With the line stopped,ovens are automatically switched to reduced power to further limit energy consumption. 
  • The resin surface is irradiated homogeneously evenly over the entire width, both in case of slabs and tiles. 

Lamp unit functional features

  • Each lamp unit has a power ranging from 2000 or 5000 watts. 
  • The lamps are installed-type gas-discharge high pressure. 
  • Each group has to choose between three different radiation Mercury, Gallium and Iron. 
  • Each lamp is protected by a thermal activated in the event of overheating due to improper cooling. 
  • It ‘available shutter mechanism which (a roller stops) completely shuts off the beam UV lamp while maintaining the temperature. 
  • Each lamp is equipped with an aluminum reflector made to exploit the emission of rays. 
  • A lamp holder with quick coupling facilitates replacement surgery of the bulbs.

UV resin advantages

1) EFFICIENCY/PRODUCTIVITY 

  • The hardening time of the UV single-component mastic is just 40 seconds. 
  • Single-component mastics are ideal for automatic batching and application systems because they don’t harden on the spatulas or in the injectors. 
  • Deep hardening depth thanks to the high-pressure Metal-Halide lamps used with high UV ray emission. The power output of each lamp can work both 2000 and 5000 Watts. 
  • When the material comes out of the oven the surface can immediately be polished without having to wait. 

2) VERSATILITY 

  • The UV mastic doesn’t need to be mixed with reagents or catalysers, the product is ready-for-use straight out ofthe tin. 
  • The mastic applied on the material remains in the liquidor semisolid state just as it was in the tin, so you can mould and work on the material at ease without the product hardening. 
  • The hardening only starts when the material goes into the oven, not before. 
  • The temperature of the environment or the material has no effect on the hardening. 
  • After polishing, single-component UV mastics produce a much brighter finish than bi-component mastics. 
  • When the line is stopped, the material in the oven doesn’t overheat because the oven output is turned down automatically. 
  • The homogeneous hardening of the surface is guaranteed by the aluminium reflectors that optimize and diffuse the rays over the material. 
  • The output of the oven can be adjusted to suit the feed speed. In this way, no energy is wasted and only the energy strictly required is used. 
  • Photo Electronics UV ovens are extremely compact sothey can be installed on existing polishing lines. 
  • The integrated extraction system pumps out any chemical fumes. 

The control panel on the oven lets you: 

  • turn each single lamp on/off, monitor the duration with a counter 
  • check the machine functions properly and any anomalies. 

3) SAFETY 

  • UV Ovens reduce the waste of energy and solvent styrene emissions 
  • Single-component products produce lower emissions of Volatile Organic Compounds (VOC). 
  • The fast hardening creates a barrier against solvent evaporation 
  • Photo Electronics ovens are fitted with all the screens and covers necessary to protect the work environment from UV rays.Safety first,always. 

4) ENERGY SAVING 

Using single-component mastics saves electrical energy. A UV oven consumes 20% – 40% less power than an electric IR oven (considerable energy savings)
The UV oven lets you reduce energy consumption during the production cycle. In fact, when the line stops the oven switches to low power mode (60% lower energy consumption). The next time the line starts the oven switches to 100% output immediately. 

Using ovens with UV lamps means a drastic reduction in energy consumption and solvent emissions.